In mail handling machines, moistening devices are used to wet the flap of an envelope in preparation for sealing the envelope. The water causes the glue on the envelope flap to soften and become tacky to the touch. Conventionally, the envelope is fed between two sealing rollers which press the flap against the envelope body to form the seal. Then, the envelope is transported along a transport path to a stacker device. To maintain secure control over the envelope, it is necessary to have pressure rolls spaced at a pitch along the transport path that is less than the height of the envelope. The presence of such pressure rolls makes it difficult for an envelope to be moved in a direction perpendicular to the path of transport for stacking in the desired manner.
Thus, it is an object of the subject invention to provide a pressure roller mechanism for driving a mail piece vertically then retracting without adding significant torque to a stacking apparatus.